Jerry Davis reports: See the beach closure message below from the San Mateo County Health Department. Perhaps we'll hear about this from the city, but I would imagine the Linda Mar (Pacifica State) Beach sewer overflow happened due to leakage into the sanitary sewer system from the storm drain system in the lower Linda Mar neighborhoods.
There apparently was flooding in Linda Mar, but I don't think that it was from the creek. I just checked out the flood control project where the creek rose nearly a meter above "bankfull." Note that when I took the picture above, the flood had already receded 60 or 80 centimeters, but I could see clear evidence of how high the flow had gotten. I put "bankfull" in quotes because the designed channel has a bankfull that is, I believe, significantly lower than what hydrologic inputs would create. This does allow the system to have more flood capacity, so that may have been intended.
But anyway, that amount of flooding is still not high enough to create flooding onto the streets from channel overflow, unless there's a low point I'm not aware of. The neighborhoods to the north of the creek and below Peralta depend more on pump stations at the beach to clear the storm drain system, since they are lower in elevation than the creek, and the pumps may get overloaded during intense rain events.
I do remember hearing from Scott Holmes that the city sanitary sewer system has to deal with a lot more volume during heavy rain, meaning that there's a lot of leakage from storm drains into the sanitary sewer system. Unlike San Francisco, Pacifica does not have a combined sanitary sewer/storm drain system, which is better for maintaining creek flows and habitat, but leakage clearly happens.
BEACH CLOSURES The following beaches are closed due to storm-related sewer overflows resulting in sewage impact to the beach: LINDA MAR STATE BEACH, PACIFICA: The entire length of Linda Mar Beach is closed until further notice. Signs are being posted. Samples will be collected once the storm abates. FRANCIS STATE BEACH, HALF MOON BAY: The beach fronting Francis State Beach Campground and Day Use area at the end of Kelly Avenue continuing south to 100 yards south of the Kelly Avenue drainage is closed until further notice. Signs are being posted. Samples will be collected once the storm abates.
Sewage-impacted beaches will reopen based on samples with acceptable bacteria levels as determined by San Mateo County Environmental Health. We strongly advise against any swimming/surfing anywhere along the San Mateo County coastline during a storm. We also strongly advise against swimming/surfing at any time in ocean waters within 100 yards of a flowing stormwater outfall. Chris Fogel photo, tone-mapped by Bob Pilgrim
Photos top to bottom: 1. Wires down along De Solo Avenue. 2. Arguello Boulevard flooded south of De Solo Avenue. Roadway and sidewalks totally submerged. Debris line up to front doors of residences. 3. Closer look at Arguello Boulevard (see above). 4. Linda Mar Boulevard at Highway 1. 5. Closer look at Highway 1 (see above). 6. San Pedro Creek mouth. 7. Tree down at Peralta and Linda Mar.
Confirmed report that a man was surfing November 3 at Linda Mar Beach with his son around 9:30 a.m., was hit by a surfboard, knocked out, and drowned. A witness says, "Folks at the beach were a bit shaken up. All I know about him was he was originally from Florida and was a regular."